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Hultgren NW, Zhou T, Williams DS. Machine learning-based 3D segmentation of mitochondria in polarized epithelial cells. Mitochondrion 2024; 76:101882. [PMID: 38599302 DOI: 10.1016/j.mito.2024.101882] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2023] [Revised: 03/18/2024] [Accepted: 04/07/2024] [Indexed: 04/12/2024]
Abstract
Mitochondria are dynamic organelles that alter their morphological characteristics in response to functional needs. Therefore, mitochondrial morphology is an important indicator of mitochondrial function and cellular health. Reliable segmentation of mitochondrial networks in microscopy images is a crucial initial step for further quantitative evaluation of their morphology. However, 3D mitochondrial segmentation, especially in cells with complex network morphology, such as in highly polarized cells, remains challenging. To improve the quality of 3D segmentation of mitochondria in super-resolution microscopy images, we took a machine learning approach, using 3D Trainable Weka, an ImageJ plugin. We demonstrated that, compared with other commonly used methods, our approach segmented mitochondrial networks effectively, with improved accuracy in different polarized epithelial cell models, including differentiated human retinal pigment epithelial (RPE) cells. Furthermore, using several tools for quantitative analysis following segmentation, we revealed mitochondrial fragmentation in bafilomycin-treated RPE cells.
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Affiliation(s)
- Nan W Hultgren
- Department of Ophthalmology and Stein Eye Institute, University of California, Los Angeles, CA 90095, USA.
| | - Tianli Zhou
- Department of Ophthalmology and Stein Eye Institute, University of California, Los Angeles, CA 90095, USA
| | - David S Williams
- Department of Ophthalmology and Stein Eye Institute, University of California, Los Angeles, CA 90095, USA; Department of Neurobiology, David Geffen School of Medicine at UCLA, University of California, Los Angeles, CA 90095, USA; Molecular Biology Institute, University of California, Los Angeles, CA 90095, USA; Brain Research Institute, University of California, Los Angeles, CA 90095, USA.
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2
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Luo J, Sun A, Yu Y, Pei Y, Zuo Y, Hu Z. Periplocoside P affects synaptic transmission at the neuromuscular junction and reduces synaptic excitability in Drosophila melanogaster by inhibiting V-ATPase. PEST MANAGEMENT SCIENCE 2023; 79:5044-5052. [PMID: 37556562 DOI: 10.1002/ps.7705] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/04/2023] [Revised: 08/02/2023] [Accepted: 08/04/2023] [Indexed: 08/11/2023]
Abstract
BACKGROUND Periplocoside P (PSP) is a major component of Periploca sepium Bunge known for its potent insecticidal activity. V-Type adenosine triphosphatase (V-ATPase), which is widely distributed in the cytoplasmic membranes and organelles of eukaryotic cells, plays a crucial role in synaptic excitability conduction. Previous research has shown that PSP targets the apical membrane of goblet cells in the insect midgut. However, the effects of PSP on synaptic transmission at the neuromuscular junction are often overlooked. RESULTS The bioassay revealed that Drosophila adults with different genetic backgrounds showed varying levels of susceptibility to PSP in the order: parats1 > parats1 ;DSC1-/- ≈ w1118 > DSC1-/- . Intracellular electrode recording demonstrated that PSP, similar to bafilomycin A1, had an impact on the amplitude of the excitatory junction potential (EJP) and accelerated excitability decay. Furthermore, the alteration in EJP amplitude is concentration-dependent. Another surprising discovery was that the knockout DSC1 channel showed insensitivity to PSP. CONCLUSION Our findings confirm that PSP can influence synaptic transmission at the neuromuscular junction of Drosophila larvae by targeting V-ATPase. These results provide a basis for investigating the mechanism of action of PSP and its potential application in designing novel insecticides. © 2023 Society of Chemical Industry.
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Affiliation(s)
- Jiaojiao Luo
- Institute of Pesticide Science, College of Plant Protection, Northwest A&F University, Yangling, Shaanxi, China
- Key Laboratory for Botanical Pesticide R&D of Shaanxi Province, Northwest A&F University, Yangling, Shaanxi, China
| | - Anqi Sun
- Institute of Pesticide Science, College of Plant Protection, Northwest A&F University, Yangling, Shaanxi, China
- Key Laboratory for Botanical Pesticide R&D of Shaanxi Province, Northwest A&F University, Yangling, Shaanxi, China
| | - Yang Yu
- Institute of Pesticide Science, College of Plant Protection, Northwest A&F University, Yangling, Shaanxi, China
- Key Laboratory for Botanical Pesticide R&D of Shaanxi Province, Northwest A&F University, Yangling, Shaanxi, China
| | - Yakun Pei
- Institute of Pesticide Science, College of Plant Protection, Northwest A&F University, Yangling, Shaanxi, China
- Key Laboratory for Botanical Pesticide R&D of Shaanxi Province, Northwest A&F University, Yangling, Shaanxi, China
| | - Yayun Zuo
- Institute of Pesticide Science, College of Plant Protection, Northwest A&F University, Yangling, Shaanxi, China
- Key Laboratory for Botanical Pesticide R&D of Shaanxi Province, Northwest A&F University, Yangling, Shaanxi, China
- Key Laboratory of Plant Protection Resources and Pest Management of Ministry of Education, Northwest A&F Univeristy, Yangling, Shaanxi, China
| | - Zhaonong Hu
- Institute of Pesticide Science, College of Plant Protection, Northwest A&F University, Yangling, Shaanxi, China
- Key Laboratory for Botanical Pesticide R&D of Shaanxi Province, Northwest A&F University, Yangling, Shaanxi, China
- Key Laboratory of Plant Protection Resources and Pest Management of Ministry of Education, Northwest A&F Univeristy, Yangling, Shaanxi, China
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Ávalos Y, Hernández-Cáceres MP, Lagos P, Pinto-Nuñez D, Rivera P, Burgos P, Díaz-Castro F, Joy-Immediato M, Venegas-Zamora L, Lopez-Gallardo E, Kretschmar C, Batista-Gonzalez A, Cifuentes-Araneda F, Toledo-Valenzuela L, Rodriguez-Peña M, Espinoza-Caicedo J, Perez-Leighton C, Bertocchi C, Cerda M, Troncoso R, Parra V, Budini M, Burgos PV, Criollo A, Morselli E. Palmitic acid control of ciliogenesis modulates insulin signaling in hypothalamic neurons through an autophagy-dependent mechanism. Cell Death Dis 2022; 13:659. [PMID: 35902579 PMCID: PMC9334645 DOI: 10.1038/s41419-022-05109-9] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2022] [Revised: 07/14/2022] [Accepted: 07/15/2022] [Indexed: 01/21/2023]
Abstract
Palmitic acid (PA) is significantly increased in the hypothalamus of mice, when fed chronically with a high-fat diet (HFD). PA impairs insulin signaling in hypothalamic neurons, by a mechanism dependent on autophagy, a process of lysosomal-mediated degradation of cytoplasmic material. In addition, previous work shows a crosstalk between autophagy and the primary cilium (hereafter cilium), an antenna-like structure on the cell surface that acts as a signaling platform for the cell. Ciliopathies, human diseases characterized by cilia dysfunction, manifest, type 2 diabetes, among other features, suggesting a role of the cilium in insulin signaling. Cilium depletion in hypothalamic pro-opiomelanocortin (POMC) neurons triggers obesity and insulin resistance in mice, the same phenotype as mice deficient in autophagy in POMC neurons. Here we investigated the effect of chronic consumption of HFD on cilia; and our results indicate that chronic feeding with HFD reduces the percentage of cilia in hypothalamic POMC neurons. This effect may be due to an increased amount of PA, as treatment with this saturated fatty acid in vitro reduces the percentage of ciliated cells and cilia length in hypothalamic neurons. Importantly, the same effect of cilia depletion was obtained following chemical and genetic inhibition of autophagy, indicating autophagy is required for ciliogenesis. We further demonstrate a role for the cilium in insulin sensitivity, as cilium loss in hypothalamic neuronal cells disrupts insulin signaling and insulin-dependent glucose uptake, an effect that correlates with the ciliary localization of the insulin receptor (IR). Consistently, increased percentage of ciliated hypothalamic neuronal cells promotes insulin signaling, even when cells are exposed to PA. Altogether, our results indicate that, in hypothalamic neurons, impairment of autophagy, either by PA exposure, chemical or genetic manipulation, cause cilia loss that impairs insulin sensitivity.
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Affiliation(s)
- Yenniffer Ávalos
- grid.412179.80000 0001 2191 5013Departamento de Biología, Facultad de Química y Biología, Universidad de Santiago de Chile, Santiago, Chile
| | - María Paz Hernández-Cáceres
- grid.7870.80000 0001 2157 0406Laboratory of Autophagy and Metabolism, Department of Physiology, Faculty of Biological Sciences, Pontificia Universidad Católica de Chile, Santiago, Chile ,grid.443909.30000 0004 0385 4466Cellular and Molecular Biology Laboratory, Institute in Dentistry Sciences, Dentistry Faculty, Universidad de Chile, Santiago, Chile
| | - Pablo Lagos
- grid.7870.80000 0001 2157 0406Laboratory of Autophagy and Metabolism, Department of Physiology, Faculty of Biological Sciences, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Daniela Pinto-Nuñez
- grid.7870.80000 0001 2157 0406Laboratory of Autophagy and Metabolism, Department of Physiology, Faculty of Biological Sciences, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Patricia Rivera
- grid.7870.80000 0001 2157 0406Laboratory of Autophagy and Metabolism, Department of Physiology, Faculty of Biological Sciences, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Paulina Burgos
- grid.7870.80000 0001 2157 0406Laboratory of Autophagy and Metabolism, Department of Physiology, Faculty of Biological Sciences, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Francisco Díaz-Castro
- grid.7870.80000 0001 2157 0406Laboratory of Autophagy and Metabolism, Department of Physiology, Faculty of Biological Sciences, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Michelle Joy-Immediato
- grid.7870.80000 0001 2157 0406Laboratory for Molecular Mechanics of Cell Adhesion, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Leslye Venegas-Zamora
- grid.443909.30000 0004 0385 4466Advanced Center for Chronic Diseases (ACCDiS), Faculty of Chemical and Pharmaceutical Sciences and Faculty of Medicine, Universidad de Chile, Santiago, Chile
| | - Erik Lopez-Gallardo
- grid.443909.30000 0004 0385 4466Advanced Center for Chronic Diseases (ACCDiS), Faculty of Chemical and Pharmaceutical Sciences and Faculty of Medicine, Universidad de Chile, Santiago, Chile
| | - Catalina Kretschmar
- grid.443909.30000 0004 0385 4466Cellular and Molecular Biology Laboratory, Institute in Dentistry Sciences, Dentistry Faculty, Universidad de Chile, Santiago, Chile
| | - Ana Batista-Gonzalez
- grid.443909.30000 0004 0385 4466Cellular and Molecular Biology Laboratory, Institute in Dentistry Sciences, Dentistry Faculty, Universidad de Chile, Santiago, Chile
| | - Flavia Cifuentes-Araneda
- grid.7870.80000 0001 2157 0406Laboratory of Autophagy and Metabolism, Department of Physiology, Faculty of Biological Sciences, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Lilian Toledo-Valenzuela
- grid.7870.80000 0001 2157 0406Laboratory of Autophagy and Metabolism, Department of Physiology, Faculty of Biological Sciences, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Marcelo Rodriguez-Peña
- grid.443909.30000 0004 0385 4466Cellular and Molecular Biology Laboratory, Institute in Dentistry Sciences, Dentistry Faculty, Universidad de Chile, Santiago, Chile
| | - Jasson Espinoza-Caicedo
- grid.7870.80000 0001 2157 0406Laboratory of Autophagy and Metabolism, Department of Physiology, Faculty of Biological Sciences, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Claudio Perez-Leighton
- grid.7870.80000 0001 2157 0406Department of Physiology, Faculty of Biological Sciences, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Cristina Bertocchi
- grid.7870.80000 0001 2157 0406Laboratory for Molecular Mechanics of Cell Adhesion, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Mauricio Cerda
- grid.443909.30000 0004 0385 4466Integrative Biology Program, Institute of Biomedical Sciences, Facultad de Medicina, Universidad de Chile, Santiago, Chile ,grid.443909.30000 0004 0385 4466Center for Medical Informatics and Telemedicine, Facultad de Medicina, Universidad de Chile, Santiago, Chile ,grid.443909.30000 0004 0385 4466Biomedical Neuroscience Institute, Santiago, Chile
| | - Rodrigo Troncoso
- grid.443909.30000 0004 0385 4466Advanced Center for Chronic Diseases (ACCDiS), Faculty of Chemical and Pharmaceutical Sciences and Faculty of Medicine, Universidad de Chile, Santiago, Chile ,grid.443909.30000 0004 0385 4466Instituto de Nutrición y Tecnología de los Alimentos (INTA), Universidad de Chile, Santiago, Chile ,Autophagy Research Center, Santiago, Chile
| | - Valentina Parra
- grid.443909.30000 0004 0385 4466Advanced Center for Chronic Diseases (ACCDiS), Faculty of Chemical and Pharmaceutical Sciences and Faculty of Medicine, Universidad de Chile, Santiago, Chile ,Autophagy Research Center, Santiago, Chile ,grid.443909.30000 0004 0385 4466Network for the Study of High-Lethality Cardiopulmonary Diseases (REECPAL), Universidad de Chile, Santiago, Chile
| | - Mauricio Budini
- Autophagy Research Center, Santiago, Chile ,grid.443909.30000 0004 0385 4466Laboratory of Molecular and Cellular Pathology, Institute in Dentistry Sciences, Dentistry Faculty, Universidad de Chile, Santiago, Chile
| | - Patricia V. Burgos
- Autophagy Research Center, Santiago, Chile ,grid.442215.40000 0001 2227 4297Centro de Biología Celular y Biomedicina (CEBICEM), Facultad de Medicina y Ciencia, Universidad San Sebastián, Santiago, Chile ,grid.7870.80000 0001 2157 0406Centro de Envejecimiento y Regeneración (CARE-UC), Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Alfredo Criollo
- grid.443909.30000 0004 0385 4466Cellular and Molecular Biology Laboratory, Institute in Dentistry Sciences, Dentistry Faculty, Universidad de Chile, Santiago, Chile ,grid.443909.30000 0004 0385 4466Advanced Center for Chronic Diseases (ACCDiS), Faculty of Chemical and Pharmaceutical Sciences and Faculty of Medicine, Universidad de Chile, Santiago, Chile ,Autophagy Research Center, Santiago, Chile
| | - Eugenia Morselli
- grid.7870.80000 0001 2157 0406Laboratory of Autophagy and Metabolism, Department of Physiology, Faculty of Biological Sciences, Pontificia Universidad Católica de Chile, Santiago, Chile ,Autophagy Research Center, Santiago, Chile ,grid.442215.40000 0001 2227 4297Department of Basic Sciences, Faculty of Medicine and Sciences, Universidad San Sebastián, Santiago, Chile
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Martinez-Fabregas J, Tamargo-Azpilicueta J, Diaz-Moreno I. Lysosomes: Multifunctional compartments ruled by a complex regulatory network. FEBS Open Bio 2022; 12:758-774. [PMID: 35218162 PMCID: PMC8972048 DOI: 10.1002/2211-5463.13387] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2021] [Revised: 02/08/2022] [Accepted: 02/24/2022] [Indexed: 11/23/2022] Open
Abstract
More than 50 years have passed since Nobel laureate Cristian de Duve described for the first time the presence of tiny subcellular compartments filled with hydrolytic enzymes: the lysosome. For a long time, lysosomes were deemed simple waste bags exerting a plethora of hydrolytic activities involved in the recycling of biopolymers, and lysosomal genes were considered to just be simple housekeeping genes, transcribed in a constitutive fashion. However, lysosomes are emerging as multifunctional signalling hubs involved in multiple aspects of cell biology, both under homeostatic and pathological conditions. Lysosomes are involved in the regulation of cell metabolism through the mTOR/TFEB axis. They are also key players in the regulation and onset of the immune response. Furthermore, it is becoming clear that lysosomal hydrolases can regulate several biological processes outside of the lysosome. They are also implicated in a complex communication network among subcellular compartments that involves intimate organelle‐to‐organelle contacts. Furthermore, lysosomal dysfunction is nowadays accepted as the causative event behind several human pathologies: low frequency inherited diseases, cancer, or neurodegenerative, metabolic, inflammatory, and autoimmune diseases. Recent advances in our knowledge of the complex biology of lysosomes have established them as promising therapeutic targets for the treatment of different pathologies. Although recent discoveries have started to highlight that lysosomes are controlled by a complex web of regulatory networks, which in some cases seem to be cell‐ and stimuli‐dependent, to harness the full potential of lysosomes as therapeutic targets, we need a deeper understanding of the little‐known signalling pathways regulating this subcellular compartment and its functions.
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Affiliation(s)
- Jonathan Martinez-Fabregas
- Instituto de Investigaciones Químicas (IIQ) - Centro de Investigaciones Científicas Isla de la Cartuja (cicCartuja), Universidad de Sevilla - CSIC, Avda. Américo Vespucio 49, 41092, Sevilla, Spain
| | - Joaquin Tamargo-Azpilicueta
- Instituto de Investigaciones Químicas (IIQ) - Centro de Investigaciones Científicas Isla de la Cartuja (cicCartuja), Universidad de Sevilla - CSIC, Avda. Américo Vespucio 49, 41092, Sevilla, Spain
| | - Irene Diaz-Moreno
- Instituto de Investigaciones Químicas (IIQ) - Centro de Investigaciones Científicas Isla de la Cartuja (cicCartuja), Universidad de Sevilla - CSIC, Avda. Américo Vespucio 49, 41092, Sevilla, Spain
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Kesharwani A, Schwarz K, Dembla E, Dembla M, Schmitz F. Early Changes in Exo- and Endocytosis in the EAE Mouse Model of Multiple Sclerosis Correlate with Decreased Synaptic Ribbon Size and Reduced Ribbon-Associated Vesicle Pools in Rod Photoreceptor Synapses. Int J Mol Sci 2021; 22:ijms221910789. [PMID: 34639129 PMCID: PMC8509850 DOI: 10.3390/ijms221910789] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2021] [Revised: 09/29/2021] [Accepted: 10/01/2021] [Indexed: 12/17/2022] Open
Abstract
Multiple sclerosis (MS) is an inflammatory disease of the central nervous system that finally leads to demyelination. Demyelinating optic neuritis is a frequent symptom in MS. Recent studies also revealed synapse dysfunctions in MS patients and MS mouse models. We previously reported alterations of photoreceptor ribbon synapses in the experimental auto-immune encephalomyelitis (EAE) mouse model of MS. In the present study, we found that the previously observed decreased imunosignals of photoreceptor ribbons in early EAE resulted from a decrease in synaptic ribbon size, whereas the number/density of ribbons in photoreceptor synapses remained unchanged. Smaller photoreceptor ribbons are associated with fewer docked and ribbon-associated vesicles. At a functional level, depolarization-evoked exocytosis as monitored by optical recording was diminished even as early as on day 7 after EAE induction. Moreover compensatory, post-depolarization endocytosis was decreased. Decreased post-depolarization endocytosis in early EAE correlated with diminished synaptic enrichment of dynamin3. In contrast, basal endocytosis in photoreceptor synapses of resting non-depolarized retinal slices was increased in early EAE. Increased basal endocytosis correlated with increased de-phosphorylation of dynamin1. Thus, multiple endocytic pathways in photoreceptor synapse are differentially affected in early EAE and likely contribute to the observed synapse pathology in early EAE.
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Affiliation(s)
- Ajay Kesharwani
- Department of Neuroanatomy, Institute of Anatomy and Cell Biology, Medical School, Saarland University, 66421 Homburg, Germany; (K.S.); (E.D.); (M.D.); (F.S.)
- Correspondence:
| | - Karin Schwarz
- Department of Neuroanatomy, Institute of Anatomy and Cell Biology, Medical School, Saarland University, 66421 Homburg, Germany; (K.S.); (E.D.); (M.D.); (F.S.)
| | - Ekta Dembla
- Department of Neuroanatomy, Institute of Anatomy and Cell Biology, Medical School, Saarland University, 66421 Homburg, Germany; (K.S.); (E.D.); (M.D.); (F.S.)
- Department of Ophthalmology, Duke University School of Medicine, Durham, NC 27710, USA
| | - Mayur Dembla
- Department of Neuroanatomy, Institute of Anatomy and Cell Biology, Medical School, Saarland University, 66421 Homburg, Germany; (K.S.); (E.D.); (M.D.); (F.S.)
- Department of Ophthalmology, Duke University School of Medicine, Durham, NC 27710, USA
| | - Frank Schmitz
- Department of Neuroanatomy, Institute of Anatomy and Cell Biology, Medical School, Saarland University, 66421 Homburg, Germany; (K.S.); (E.D.); (M.D.); (F.S.)
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Cell Energy Budget Platform for Multiparametric Assessment of Cell and Tissue Metabolism. Methods Mol Biol 2021; 2276:305-324. [PMID: 34060051 DOI: 10.1007/978-1-0716-1266-8_23] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
Specific bioenergetic signature reports on the current metabolic state of the cell, which may be affected by metabolic rearrangement, dysfunction or dysregulation of relevant signaling pathways, altered physiological condition or energy stress. A combined analysis of respiration , glycolytic flux, Krebs cycle activity, ATP levels, and total biomass allows informative initial assessment. Such simple, high-throughput, multiparametric methodology, called cell energy budget (CEB ) platform, is presented here and demonstrated with particular cell and tissue models. The CEB uses a commercial fluorescent lanthanide probe pH-Xtra™ to measure extracellular acidification (ECA) associated with lactate (L-ECA) and combined lactate/CO2 (T-ECA), a phosphorescent probe MitoXpress®-Xtra to measure oxygen consumption rate (OCR), a bioluminescent ATP kit, and an absorbance-based total protein assay. All the assays are performed on a standard multi-label reader. Using the same readouts, the CEB approach can be extended to more detailed mechanistic studies, by targeting specific pathways in cell bioenergetics and measuring other cellular parameters, such as NAD(P)H, Ca2+, mitochondrial pH, membrane potential, redox state, with conventional fluorescent or luminescent probes.
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Dykstra KM, Fay HRS, Massey AC, Yang N, Johnson M, Portwood S, Guzman ML, Wang ES. Inhibiting autophagy targets human leukemic stem cells and hypoxic AML blasts by disrupting mitochondrial homeostasis. Blood Adv 2021; 5:2087-2100. [PMID: 33877295 PMCID: PMC8095145 DOI: 10.1182/bloodadvances.2020002666] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2020] [Accepted: 03/01/2021] [Indexed: 12/22/2022] Open
Abstract
Leukemia stem cells (LSCs) and therapy-resistant acute myeloid leukemia (AML) blasts contribute to the reinitiation of leukemia after remission, necessitating therapeutic interventions that target these populations. Autophagy is a prosurvival process that allows for cells to adapt to a variety of stressors. Blocking autophagy pharmacologically by using mechanistically distinct inhibitors induced apoptosis and prevented colony formation in primary human AML cells. The most effective inhibitor, bafilomycin A1 (Baf A1), also prevented the in vivo maintenance of AML LSCs in NSG mice. To understand why Baf A1 exerted the most dramatic effects on LSC survival, we evaluated mitochondrial function. Baf A1 reduced mitochondrial respiration and stabilized PTEN-induced kinase-1 (PINK-1), which initiates autophagy of mitochondria (mitophagy). Interestingly, with the autophagy inhibitor chloroquine, levels of enhanced cell death and reduced mitochondrial respiration phenocopied the effects of Baf A1 only when cultured in hypoxic conditions that mimic the marrow microenvironment (1% O2). This indicates that increased efficacy of autophagy inhibitors in inducing AML cell death can be achieved by concurrently inducing mitochondrial damage and mitophagy (pharmacologically or by hypoxic induction) and blocking mitochondrial degradation. In addition, prolonged exposure of AML cells to hypoxia induced autophagic flux and reduced chemosensitivity to cytarabine (Ara-C), which was reversed by autophagy inhibition. The combination of Ara-C with Baf A1 also decreased tumor burden in vivo. These findings demonstrate that autophagy is critical for mitochondrial homeostasis and survival of AML cells in hypoxia and support the development of autophagy inhibitors as novel therapeutic agents for AML.
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Affiliation(s)
| | - Hannah R S Fay
- Department of Medicine and
- Department of Immunology, Roswell Park Comprehensive Cancer Center, Buffalo, NY
| | - Ashish C Massey
- Department of Pediatrics, Memorial Sloan Kettering Cancer Center, New York, NY
- Division of Hematology and Medical Oncology, Department of Pediatrics, and
| | - Neng Yang
- Division of Hematology and Medical Oncology, Department of Medicine, Weill Cornell Medicine, New York, NY; and
| | | | | | - Monica L Guzman
- Division of Hematology and Medical Oncology, Department of Pediatrics, and
| | - Eunice S Wang
- Department of Medicine and
- Department of Immunology, Roswell Park Comprehensive Cancer Center, Buffalo, NY
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Downregulation of ATP6V1A Involved in Alzheimer's Disease via Synaptic Vesicle Cycle, Phagosome, and Oxidative Phosphorylation. OXIDATIVE MEDICINE AND CELLULAR LONGEVITY 2021; 2021:5555634. [PMID: 33981384 PMCID: PMC8087993 DOI: 10.1155/2021/5555634] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/23/2021] [Revised: 03/02/2021] [Accepted: 03/24/2021] [Indexed: 12/12/2022]
Abstract
Objective The objective of this study was to investigate the potential molecular mechanisms of ATPase H+ transporting V1 subunit A (ATP6V1A) underlying Alzheimer's disease (AD). Methods Microarray expression data of human temporal cortex samples from the GSE118553 dataset were profiled to screen for differentially expressed genes (DEGs) between AD/control and ATP6V1A-low/high groups. Correlations of coexpression modules with AD and ATP6V1A were assessed by weight gene correlation network analysis (WGCNA). DEGs strongly interacting with ATP6V1A were extracted to construct global regulatory network. Further cross-talking pathways of ATP6V1A were identified by functional enrichment analysis. Diagnostic performance of ATP6V1A in AD prediction was evaluated using area under the curve (AUC) analysis. Results The mean expression of ATP6V1A was significantly downregulated in AD compared with nondementia controls. A total of 1,364 DEGs were overlapped from AD/control and ATP6V1A-low/high groups. Based on these DEGs, four coexpression modules were predicted by WGCNA. The blue, brown, and turquoise modules were significantly correlated with AD and low ATP6V1A, whose DEGs were enriched in phagosome, oxidative phosphorylation, synaptic vesicle cycle, focal adhesion, and gamma-aminobutyric acidergic (GABAergic) synapse. Global regulatory network was constructed to identify the cross-talking pathways of ATP6V1A, such as synaptic vesicle cycle, phagosome, and oxidative phosphorylation. According to the AUC value of 74.2%, low ATP6V1A expression accurately predicted the occurrence of AD. Conclusions Our findings highlighted the pleiotropic roles of low ATP6V1A in AD pathogenesis, possibly mediated by synaptic vesicle cycle, phagosome, and oxidative phosphorylation.
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Mueller BJ, Zhdanov AV, Borisov SM, Foley T, Okkelman IA, Tsytsarev V, Tang Q, Erzurumlu RS, Chen Y, Zhang H, Toncelli C, Klimant I, Papkovsky DB, Dmitriev RI. Nanoparticle-based fluoroionophore for analysis of potassium ion dynamics in 3D tissue models and in vivo. ADVANCED FUNCTIONAL MATERIALS 2018; 28:1704598. [PMID: 30271316 PMCID: PMC6157274 DOI: 10.1002/adfm.201704598] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
The imaging of real-time fluxes of K+ ions in live cell with high dynamic range (5-150 mM) is of paramount importance for neuroscience and physiology of the gastrointestinal tract, kidney and other tissues. In particular, the research on high-performance deep-red fluorescent nanoparticle-based biosensors is highly anticipated. We found that BODIPY-based FI3 K+-sensitive fluoroionophore encapsulated in cationic polymer RL100 nanoparticles displays unusually strong efficiency in staining of broad spectrum of cell models, such as primary neurons and intestinal organoids. Using comparison of brightness, photostability and fluorescence lifetime imaging microscopy (FLIM) we confirmed that FI3 nanoparticles display distinctively superior intracellular staining compared to the free dye. We evaluated FI3 nanoparticles in real-time live cell imaging and found that it is highly useful for monitoring intra- and extracellular K+ dynamics in cultured neurons. Proof-of-concept in vivo brain imaging confirmed applicability of the biosensor for visualization of epileptic seizures. Collectively, this data makes fluoroionophore FI3 a versatile cross-platform fluorescent biosensor, broadly compatible with diverse experimental models and that crown ether-based polymer nanoparticles can provide a new venue for design of efficient fluorescent probes.
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Affiliation(s)
- Bernhard J. Mueller
- Institute of Analytical Chemistry and Food Chemistry, Graz University of Technology, Stremayrgasse 9, 8010 Graz, Austria
| | - Alexander V. Zhdanov
- ABCRF, School of Biochemistry and Cell biology, University College Cork, Cork, Ireland
| | - Sergey M. Borisov
- Institute of Analytical Chemistry and Food Chemistry, Graz University of Technology, Stremayrgasse 9, 8010 Graz, Austria
| | - Tara Foley
- Department of Anatomy and Neuroscience, University College Cork, Cork, Ireland
| | - Irina A. Okkelman
- ABCRF, School of Biochemistry and Cell biology, University College Cork, Cork, Ireland
| | - Vassiliy Tsytsarev
- Department of Anatomy and Neurobiology, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Qinggong Tang
- Fischell Department of Bioengineering, University of Maryland, College Park, 20740 MD, USA
| | - Reha S. Erzurumlu
- Department of Anatomy and Neurobiology, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Yu Chen
- Fischell Department of Bioengineering, University of Maryland, College Park, 20740 MD, USA
| | - Haijiang Zhang
- Empa, Swiss Federal Laboratories for Materials Science and Technology, Laboratory for Biomimetic Membranes and Textiles, Lerchenfeldstrasse 5, CH-9014 St. Gallen, Switzerland
| | - Claudio Toncelli
- Empa, Swiss Federal Laboratories for Materials Science and Technology, Laboratory for Biomimetic Membranes and Textiles, Lerchenfeldstrasse 5, CH-9014 St. Gallen, Switzerland
| | - Ingo Klimant
- Institute of Analytical Chemistry and Food Chemistry, Graz University of Technology, Stremayrgasse 9, 8010 Graz, Austria
| | - Dmitri B. Papkovsky
- ABCRF, School of Biochemistry and Cell biology, University College Cork, Cork, Ireland
| | - Ruslan I. Dmitriev
- ABCRF, School of Biochemistry and Cell biology, University College Cork, Cork, Ireland
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10
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Demine S, Tejerina S, Bihin B, Thiry M, Reddy N, Renard P, Raes M, Jadot M, Arnould T. Mild mitochondrial uncoupling induces HSL/ATGL-independent lipolysis relying on a form of autophagy in 3T3-L1 adipocytes. J Cell Physiol 2017; 233:1247-1265. [PMID: 28488768 DOI: 10.1002/jcp.25994] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2016] [Accepted: 05/08/2017] [Indexed: 12/15/2022]
Abstract
Obesity is characterized by an excessive triacylglycerol accumulation in white adipocytes. Various mechanisms allowing the tight regulation of triacylglycerol storage and mobilization by lipid droplet-associated proteins as well as lipolytic enzymes have been identified. Increasing energy expenditure by inducing a mild uncoupling of mitochondria in adipocytes might represent a putative interesting anti-obesity strategy as it reduces the adipose tissue triacylglycerol content (limiting alterations caused by cell hypertrophy) by stimulating lipolysis through yet unknown mechanisms, limiting the adverse effects of adipocyte hypertrophy. Herein, the molecular mechanisms involved in lipolysis induced by a mild uncoupling of mitochondria in white 3T3-L1 adipocytes were characterized. Mitochondrial uncoupling-induced lipolysis was found to be independent from canonical pathways that involve lipolytic enzymes such as HSL and ATGL. Finally, enhanced lipolysis in response to mitochondrial uncoupling relies on a form of autophagy as lipid droplets are captured by endolysosomal vesicles. This new mechanism of triacylglycerol breakdown in adipocytes exposed to mild uncoupling provides new insights on the biology of adipocytes dealing with mitochondria forced to dissipate energy.
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Affiliation(s)
- Stéphane Demine
- Laboratory of Biochemistry and Cell Biology (URBC), NARILIS (Namur Research Institute for Life Sciences), University of Namur (UNamur), Namur, Belgium
| | - Silvia Tejerina
- Laboratory of Biochemistry and Cell Biology (URBC), NARILIS (Namur Research Institute for Life Sciences), University of Namur (UNamur), Namur, Belgium
| | - Benoît Bihin
- Laboratory of Biochemistry and Cell Biology (URBC), NARILIS (Namur Research Institute for Life Sciences), University of Namur (UNamur), Namur, Belgium
| | - Marc Thiry
- Laboratory of Cell Biology, GIGA-R, University of Liège, Liège, Belgium
| | - Nagabushana Reddy
- Laboratory of Biochemistry and Cell Biology (URBC), NARILIS (Namur Research Institute for Life Sciences), University of Namur (UNamur), Namur, Belgium
| | - Patricia Renard
- Laboratory of Biochemistry and Cell Biology (URBC), NARILIS (Namur Research Institute for Life Sciences), University of Namur (UNamur), Namur, Belgium
| | - Martine Raes
- Laboratory of Biochemistry and Cell Biology (URBC), NARILIS (Namur Research Institute for Life Sciences), University of Namur (UNamur), Namur, Belgium
| | - Michel Jadot
- Laboratory of Molecular Physiology (URPhyM), NARILIS (Namur Research Institute for Life Sciences), University of Namur (UNamur), Namur, Belgium
| | - Thierry Arnould
- Laboratory of Biochemistry and Cell Biology (URBC), NARILIS (Namur Research Institute for Life Sciences), University of Namur (UNamur), Namur, Belgium
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11
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Zhdanov AV, Andreev DE, Baranov PV, Papkovsky DB. Low energy costs of F1Fo ATP synthase reversal in colon carcinoma cells deficient in mitochondrial complex IV. Free Radic Biol Med 2017; 106:184-195. [PMID: 28189850 DOI: 10.1016/j.freeradbiomed.2017.02.025] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/17/2016] [Revised: 02/08/2017] [Accepted: 02/08/2017] [Indexed: 10/20/2022]
Abstract
Mitochondrial polarisation is paramount for a variety of cellular functions. Under ischemia, mitochondrial membrane potential (ΔΨm) and proton gradient (ΔpH) are maintained via a reversal of mitochondrial F1Fo ATP synthase (mATPase), which can rapidly deplete ATP and drive cells into energy crisis. We found that under normal conditions in cells with disassembled cytochrome c oxidase complex (COX-deficient HCT116), mATPase maintains ΔΨm at levels only 15-20% lower than in WT cells, and for this utilises relatively little ATP. For a small energy expenditure, mATPase enables mitochondrial ΔpH, protein import, Ca2+ turnover, and supports free radical detoxication machinery enlarged to protect the cells from oxidative damage. Whereas in COX-deficient cells the main source of ATP is glycolysis, the ΔΨm is still maintained upon inhibition of the adenine nucleotide translocators with bongkrekic acid and carboxyatractyloside, indicating that the role of ANTs is redundant, and matrix substrate level phosphorylation alone or in cooperation with ATP-Mg/Pi carriers can continuously support the mATPase activity. Intriguingly, we found that mitochondrial complex III is active, and it contributes not only to free radical production, but also to ΔΨm maintenance and energy budget of COX-deficient cells. Overall, this study demonstrates that F1Fo ATP synthase can support general mitochondrial and cellular functions, working in extremely efficient 'energy saving' reverse mode and flexibly recruiting free radical detoxication and ATP producing / transporting pathways.
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Affiliation(s)
- Alexander V Zhdanov
- School of Biochemistry & Cell Biology, University College Cork, Cork, Ireland.
| | - Dmitry E Andreev
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, Russia
| | - Pavel V Baranov
- School of Biochemistry & Cell Biology, University College Cork, Cork, Ireland
| | - Dmitri B Papkovsky
- School of Biochemistry & Cell Biology, University College Cork, Cork, Ireland
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12
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Redmann M, Benavides GA, Berryhill TF, Wani WY, Ouyang X, Johnson MS, Ravi S, Barnes S, Darley-Usmar VM, Zhang J. Inhibition of autophagy with bafilomycin and chloroquine decreases mitochondrial quality and bioenergetic function in primary neurons. Redox Biol 2016; 11:73-81. [PMID: 27889640 PMCID: PMC5124357 DOI: 10.1016/j.redox.2016.11.004] [Citation(s) in RCA: 171] [Impact Index Per Article: 21.4] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2016] [Revised: 11/07/2016] [Accepted: 11/09/2016] [Indexed: 12/20/2022] Open
Abstract
Autophagy is an important cell recycling program responsible for the clearance of damaged or long-lived proteins and organelles. Pharmacological modulators of this pathway have been extensively utilized in a wide range of basic research and pre-clinical studies. Bafilomycin A1 and chloroquine are commonly used compounds that inhibit autophagy by targeting the lysosomes but through distinct mechanisms. Since it is now clear that mitochondrial quality control, particularly in neurons, is dependent on autophagy, it is important to determine whether these compounds modify cellular bioenergetics. To address this, we cultured primary rat cortical neurons from E18 embryos and used the Seahorse XF96 analyzer and a targeted metabolomics approach to measure the effects of bafilomycin A1 and chloroquine on bioenergetics and metabolism. We found that both bafilomycin and chloroquine could significantly increase the autophagosome marker LC3-II and inhibit key parameters of mitochondrial function, and increase mtDNA damage. Furthermore, we observed significant alterations in TCA cycle intermediates, particularly those downstream of citrate synthase and those linked to glutaminolysis. Taken together, these data demonstrate a significant impact of bafilomycin and chloroquine on cellular bioenergetics and metabolism consistent with decreased mitochondrial quality associated with inhibition of autophagy. Autophagy inhibition decreased mitochondrial bioenergetics in intact neurons. Autophagy inhibition decreased mitochondrial complexes I, II or IV substrate linked respiration. Autophagy inhibition increased mitochondrial DNA damage. Autophagy inhibition decreased major components of the Krebs cycle. Autophagy inhibition resulted in decreased citrate synthase activities.
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Affiliation(s)
- Matthew Redmann
- Department of Pathology and Center for Free Radical Biology, University of Alabama at Birmingham, Birmingham, AL 35294, United States
| | - Gloria A Benavides
- Department of Pathology and Center for Free Radical Biology, University of Alabama at Birmingham, Birmingham, AL 35294, United States
| | - Taylor F Berryhill
- Targeted Metabolomics & Proteomics Laboratory, University of Alabama at Birmingham, Birmingham, AL 35294, United States
| | - Willayat Y Wani
- Department of Pathology and Center for Free Radical Biology, University of Alabama at Birmingham, Birmingham, AL 35294, United States
| | - Xiaosen Ouyang
- Department of Pathology and Center for Free Radical Biology, University of Alabama at Birmingham, Birmingham, AL 35294, United States
| | - Michelle S Johnson
- Department of Pathology and Center for Free Radical Biology, University of Alabama at Birmingham, Birmingham, AL 35294, United States
| | - Saranya Ravi
- Department of Pathology and Center for Free Radical Biology, University of Alabama at Birmingham, Birmingham, AL 35294, United States
| | - Stephen Barnes
- Targeted Metabolomics & Proteomics Laboratory, University of Alabama at Birmingham, Birmingham, AL 35294, United States
| | - Victor M Darley-Usmar
- Department of Pathology and Center for Free Radical Biology, University of Alabama at Birmingham, Birmingham, AL 35294, United States
| | - Jianhua Zhang
- Department of Pathology and Center for Free Radical Biology, University of Alabama at Birmingham, Birmingham, AL 35294, United States; VA Medical Center, University of Alabama at Birmingham, Birmingham, AL 35294, United States.
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13
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Song T, Jeon HK, Hong JE, Choi JJ, Kim TJ, Choi CH, Bae DS, Kim BG, Lee JW. Proton Pump Inhibition Enhances the Cytotoxicity of Paclitaxel in Cervical Cancer. Cancer Res Treat 2016; 49:595-606. [PMID: 27669706 PMCID: PMC5512380 DOI: 10.4143/crt.2016.034] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2016] [Accepted: 09/11/2016] [Indexed: 12/23/2022] Open
Abstract
Purpose This study was conducted to investigate whether a proton pump inhibitor (PPI) could enhance chemosensitivity via the inhibition of vacuolar-type H+ ATPase (V-ATPase) in cervical cancer. Materials and Methods The expression of V-ATPase was evaluated in 351 formalin-fixed, paraffin-embedded human cervical cancer tissues using immunohistochemistry and compared with clinicopathologic risk factors for disease prognosis. The influence of cell proliferation and apoptosis following V-ATPase siRNA transfection or esomeprazole pretreatment was assessed in cervical cancer cell lines using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide and enzyme-linked immunosorbent assay, respectively. Results Immunohistochemical analysis revealed that V-ATPase was expressed in about 60% of cervical cancer tissue samples (211/351), and the expression was predominantly found in adenocarcinoma histology (p=0.016). Among patients with initially bulky cervical cancer (n=89), those with V-ATPase expression had shorter disease-free survival (p=0.005) and overall survival (p=0.023). Co-treatment with V-ATPase siRNA or esomeprazole with paclitaxel significantly decreased the cell proliferation of cervical cancer cell lines, including HeLa and INT407, compared to cell lines treated with paclitaxel alone (p < 0.01). Moreover, V-ATPase siRNA or esomeprazole followed by paclitaxel significantly increased the expression of active caspase-3 in these cells compared to cells treated with paclitaxel alone (both, p < 0.05). Conclusion V-ATPase was predominantly expressed in cervical adenocarcinoma, and the expression of V-ATPases was associated with poor prognosis. The inhibition of V-ATPase via siRNA or PPI (esomeprazole) might enhance the chemosensitivity of paclitaxel in cervical cancer cells.
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Affiliation(s)
- Taejong Song
- Department of Obstetrics and Gynecology, Kangbuk Samsung Hospital, Sungkyunkwan University School of Medicine, Seoul, Korea
| | - Hye-Kyung Jeon
- Department of Obstetrics and Gynecology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea
| | - Ji Eun Hong
- Department of Obstetrics and Gynecology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea
| | - Jung-Joo Choi
- Department of Obstetrics and Gynecology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea
| | - Tae-Joong Kim
- Department of Obstetrics and Gynecology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea
| | - Chel Hun Choi
- Department of Obstetrics and Gynecology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea
| | - Duk-Soo Bae
- Department of Obstetrics and Gynecology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea
| | - Byoung-Gie Kim
- Department of Obstetrics and Gynecology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea
| | - Jeong-Won Lee
- Department of Obstetrics and Gynecology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea
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14
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Lee YY, Jeon HK, Hong JE, Cho YJ, Ryu JY, Choi JJ, Lee SH, Yoon G, Kim WY, Do IG, Kim MK, Kim TJ, Choi CH, Lee JW, Bae DS, Kim BG. Proton pump inhibitors enhance the effects of cytotoxic agents in chemoresistant epithelial ovarian carcinoma. Oncotarget 2016; 6:35040-50. [PMID: 26418900 PMCID: PMC4741507 DOI: 10.18632/oncotarget.5319] [Citation(s) in RCA: 42] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2015] [Accepted: 09/07/2015] [Indexed: 11/25/2022] Open
Abstract
This study was designed to investigate whether proton pump inhibitors (PPI, V-ATPase blocker) could increase the effect of cytotoxic agents in chemoresistant epithelial ovarian cancer (EOC). Expression of V-ATPase protein was evaluated in patients with EOC using immunohistochemistry, and patient survival was compared based on expression of V-ATPase mRNA from a TCGA data set. In vitro, EOC cell lines were treated with chemotherapeutic agents with or without V-ATPase siRNA or PPI (omeprazole) pretreatment. Cell survival and apoptosis was assessed using MTT assay and ELISA, respectively. In vivo experiments were performed to confirm the synergistic effect with omeprazole and paclitaxel on tumor growth in orthotopic and patient-derived xenograft (PDX) mouse models. Expression of V-ATPase protein in ovarian cancer tissues was observed in 44 patients (44/59, 74.6%). Higher expression of V-ATPase mRNA was associated with poorer overall survival in TCGA data. Inhibition of V-ATPase by siRNA or omeprazole significantly increased cytotoxicity or apoptosis to paclitaxel in chemoresistant (HeyA8-MDR, SKOV3-TR) and clear cell carcinoma cells (ES-2, RMG-1), but not in chemosensitive cells (HeyA8, SKOV3ip1). Moreover, the combination of omeprazole and paclitaxel significantly decreased the total tumor weight compared with paclitaxel alone in a chemoresistant EOC animal model and a PDX model of clear cell carcinoma. However, this finding was not observed in chemosensitive EOC animal models. These results show that omeprazole pretreatment can increase the effect of chemotherapeutic agents in chemoresistant EOC and clear cell carcinoma via reduction of the acidic tumor microenvironment.
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Affiliation(s)
- Yoo-Young Lee
- Department of Obstetrics and Gynecology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea
| | - Hye-Kyung Jeon
- Department of Obstetrics and Gynecology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea
| | - Ji Eun Hong
- Department of Obstetrics and Gynecology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea
| | - Young Jae Cho
- Department of Obstetrics and Gynecology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea
| | - Ji Yoon Ryu
- Department of Obstetrics and Gynecology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea
| | - Jung-Joo Choi
- Department of Obstetrics and Gynecology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea
| | - Sang Hoon Lee
- Department of Obstetrics and Gynecology, Chung-Ang University School of Medicine, Seoul, Korea
| | - Gun Yoon
- Department of Obstetrics and Gynecology, Pusan National University Yangsan Hospital, Pusan National University School of Medicine, Yangsan, Korea
| | - Woo Young Kim
- Department of Obstetrics and Gynecology, Kangbuk Samsung Hospital, Sungkyunkwan University School of Medicine, Seoul, Korea
| | - In-Gu Do
- Department of Pathology, Kangbuk Samsung Hospital, Sungkyunkwan University School of Medicine, Seoul, Korea
| | - Min Kyu Kim
- Department of Obstetrics and Gynecology, Samsung Changwon Hospital, Sungkyunkwan University School of Medicine, Changwon, Korea
| | - Tae-Joong Kim
- Department of Obstetrics and Gynecology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea
| | - Chel Hun Choi
- Department of Obstetrics and Gynecology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea
| | - Jeong-Won Lee
- Department of Obstetrics and Gynecology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea
| | - Duk-Soo Bae
- Department of Obstetrics and Gynecology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea
| | - Byoung-Gie Kim
- Department of Obstetrics and Gynecology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea
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15
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Zhdanov AV, Golubeva AV, Okkelman IA, Cryan JF, Papkovsky DB. Imaging of oxygen gradients in giant umbrella cells: an ex vivo PLIM study. Am J Physiol Cell Physiol 2015; 309:C501-9. [DOI: 10.1152/ajpcell.00121.2015] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2015] [Accepted: 08/03/2015] [Indexed: 12/29/2022]
Abstract
O2 plays a pivotal role in aerobic metabolism and regulation of cell and tissue function. Local differences and fluctuations in tissue O2 levels are well documented; however, the physiological significance of O2 microgradients, particularly at the subcellular level, remains poorly understood. Using the cell-penetrating phosphorescent O2 probe Pt-Glc and confocal fluorescence microscopy, we visualized O2 distribution in individual giant (>100-μm) umbrella cells located superficially in the urinary bladder epithelium. We optimized conditions for in vivo phosphorescent staining of the inner surface of the mouse bladder and subsequent ex vivo analysis of excised live tissue. Imaging experiments revealed significant (≤85 μM) and heterogeneous deoxygenation within respiring umbrella cells, with radial O2 gradients of up to 40 μM across the cell, or ∼0.6 μM/μm. Deeply deoxygenated (5–15 μM O2) regions were seen to correspond to the areas enriched with polarized mitochondria. Pharmacological activation of mitochondrial respiration decreased oxygenation and O2 gradients in umbrella cells, while inhibition with antimycin A dissipated the gradients and caused gradual reoxygenation of the tissue to ambient levels. Detailed three-dimensional maps of O2 distribution potentially can be used for the modeling of intracellular O2-dependent enzymatic reactions and downstream processes, such as hypoxia-inducible factor signaling. Further ex vivo and in vivo studies on intracellular and tissue O2 gradients using confocal imaging can shed light on the molecular mechanisms regulating O2-dependent (patho)physiological processes in the bladder and other tissues.
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Affiliation(s)
- A. V. Zhdanov
- School of Biochemistry and Cell Biology, University College Cork, Cork, Ireland
| | - A. V. Golubeva
- Alimentary Pharmabiotic Centre, University College Cork, Cork, Ireland; and
| | - I. A. Okkelman
- School of Biochemistry and Cell Biology, University College Cork, Cork, Ireland
| | - J. F. Cryan
- Alimentary Pharmabiotic Centre, University College Cork, Cork, Ireland; and
- Department of Anatomy and Neuroscience, University College Cork, Cork, Ireland
| | - D. B. Papkovsky
- School of Biochemistry and Cell Biology, University College Cork, Cork, Ireland
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16
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Dmitriev RI, Papkovsky DB. Intracellular probes for imaging oxygen concentration: how good are they? Methods Appl Fluoresc 2015; 3:034001. [DOI: 10.1088/2050-6120/3/3/034001] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
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17
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Wei Y, An Z, Zou Z, Sumpter R, Su M, Zang X, Sinha S, Gaestel M, Levine B. The stress-responsive kinases MAPKAPK2/MAPKAPK3 activate starvation-induced autophagy through Beclin 1 phosphorylation. eLife 2015; 4:e05289. [PMID: 25693418 PMCID: PMC4337728 DOI: 10.7554/elife.05289] [Citation(s) in RCA: 136] [Impact Index Per Article: 15.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2014] [Accepted: 01/26/2015] [Indexed: 12/18/2022] Open
Abstract
Autophagy is a fundamental adaptive response to amino acid starvation orchestrated by conserved gene products, the autophagy (ATG) proteins. However, the cellular cues that activate the function of ATG proteins during amino acid starvation are incompletely understood. Here we show that two related stress-responsive kinases, members of the p38 mitogen-activated protein kinase (MAPK) signaling pathway MAPKAPK2 (MK2) and MAPKAPK3 (MK3), positively regulate starvation-induced autophagy by phosphorylating an essential ATG protein, Beclin 1, at serine 90, and that this phosphorylation site is essential for the tumor suppressor function of Beclin 1. Moreover, MK2/MK3-dependent Beclin 1 phosphorylation (and starvation-induced autophagy) is blocked in vitro and in vivo by BCL2, a negative regulator of Beclin 1. Together, these findings reveal MK2/MK3 as crucial stress-responsive kinases that promote autophagy through Beclin 1 S90 phosphorylation, and identify the blockade of MK2/3-dependent Beclin 1 S90 phosphorylation as a mechanism by which BCL2 inhibits the autophagy function of Beclin 1.
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Affiliation(s)
- Yongjie Wei
- Center for Autophagy Research, Department of Internal Medicine, UT Southwestern Medical Center, Dallas, United States
- Howard Hughes Medical Institute, UT Southwestern Medical Center, Dallas, United States
| | - Zhenyi An
- Center for Autophagy Research, Department of Internal Medicine, UT Southwestern Medical Center, Dallas, United States
| | - Zhongju Zou
- Center for Autophagy Research, Department of Internal Medicine, UT Southwestern Medical Center, Dallas, United States
- Howard Hughes Medical Institute, UT Southwestern Medical Center, Dallas, United States
| | - Rhea Sumpter
- Center for Autophagy Research, Department of Internal Medicine, UT Southwestern Medical Center, Dallas, United States
| | - Minfei Su
- Department of Chemistry and Biochemistry, North Dakota State University, Fargo, United States
| | - Xiao Zang
- Department of Clinical Sciences, UT Southwestern Medical Center, Dallas, United States
| | - Sangita Sinha
- Department of Chemistry and Biochemistry, North Dakota State University, Fargo, United States
| | - Matthias Gaestel
- Institute of Physiological Chemistry, Hannover Medical School, Hannover, Germany
| | - Beth Levine
- Center for Autophagy Research, Department of Internal Medicine, UT Southwestern Medical Center, Dallas, United States
- Howard Hughes Medical Institute, UT Southwestern Medical Center, Dallas, United States
- Department of Microbiology, UT Southwestern Medical Center, Dallas, United States
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18
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Papkovsky DB, Zhdanov AV. Cell energy budget platform for assessment of cell metabolism. Methods Mol Biol 2015; 1265:333-48. [PMID: 25634285 DOI: 10.1007/978-1-4939-2288-8_23] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Changes in bioenergetic parameters report on metabolic rearrangement, dysfunction of major pathways, and regulatory processes within the cell, adaptation to energy stress, or new physiological condition. A combined measurement of oxidative phosphorylation, glycolytic flux, the Krebs cycle activity, ATP levels, and total biomass allows detailed metabolic assessment. We describe a simple methodology for high-throughput multiparametric assessment of cell bioenergetics, called cell energy budget (CEB) platform, and demonstrate its practical use with cell models. The CEB relies on a standard multi-label reader with time-resolved fluorescence capabilities, the lanthanide probe pH-Xtra™ to measure extracellular acidification (ECA) associated with lactate (L-ECA) and combined lactate/CO2 (T-ECA) extrusion, the phosphorescent probe MitoXpress®-Xtra to measure oxygen consumption rate (OCR), the bioluminescent total ATP assay, and absorbance-based total protein assay. This approach can be further extended with the measurement of other cellular parameters, such as NAD(P)H, Ca(2+), mitochondrial pH, membrane potential, and redox state, using the corresponding fluorescent or luminescent probes.
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Affiliation(s)
- Dmitri B Papkovsky
- School of Biochemistry and Cell Biology, University College Cork, Cavanagh Pharmacy Building, Office 1.28, College Road, Cork, Ireland,
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19
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Houel-Renault L, Philippe L, Piquemal M, Ciapa B. Autophagy is used as a survival program in unfertilized sea urchin eggs that are destined to die by apoptosis after inactivation of MAPK1/3 (ERK2/1). Autophagy 2014; 9:1527-39. [DOI: 10.4161/auto.25712] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
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20
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Martin A, Byrne A, Burke CS, Forster RJ, Keyes TE. Peptide-Bridged Dinuclear Ru(II) Complex for Mitochondrial Targeted Monitoring of Dynamic Changes to Oxygen Concentration and ROS Generation in Live Mammalian Cells. J Am Chem Soc 2014; 136:15300-9. [DOI: 10.1021/ja508043q] [Citation(s) in RCA: 90] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Affiliation(s)
- Aaron Martin
- School
of Chemical Sciences, National Biophotonics and Imaging Platform, Dublin City University, Dublin 9, Ireland
| | - Aisling Byrne
- School
of Chemical Sciences, National Biophotonics and Imaging Platform, Dublin City University, Dublin 9, Ireland
| | - Christopher S. Burke
- School
of Chemical Sciences, National Biophotonics and Imaging Platform, Dublin City University, Dublin 9, Ireland
| | - Robert J. Forster
- School
of Chemical Sciences, National Biophotonics and Imaging Platform, Dublin City University, Dublin 9, Ireland
| | - Tia E. Keyes
- School
of Chemical Sciences, National Biophotonics and Imaging Platform, Dublin City University, Dublin 9, Ireland
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21
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Zhdanov AV, Waters AHC, Golubeva AV, Papkovsky DB. Differential contribution of key metabolic substrates and cellular oxygen in HIF signalling. Exp Cell Res 2014; 330:13-28. [PMID: 25447307 DOI: 10.1016/j.yexcr.2014.10.005] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2014] [Revised: 10/02/2014] [Accepted: 10/05/2014] [Indexed: 12/25/2022]
Abstract
Changes in availability and utilisation of O2 and metabolic substrates are common in ischemia and cancer. We examined effects of substrate deprivation on HIF signalling in PC12 cells exposed to different atmospheric O2. Upon 2-4h moderate hypoxia, HIF-α protein levels were dictated by the availability of glutamine and glucose, essential for deep cell deoxygenation and glycolytic ATP flux. Nuclear accumulation of HIF-1α dramatically decreased upon inhibition of glutaminolysis or glutamine deprivation. Elevation of HIF-2α levels was transcription-independent and associated with the activation of Akt and Erk1/2. Upon 2h anoxia, HIF-2α levels strongly correlated with cellular ATP, produced exclusively via glycolysis. Without glucose, HIF signalling was suppressed, giving way to other regulators of cell adaptation to energy crisis, e.g. AMPK. Consequently, viability of cells deprived of O2 and glucose decreased upon inhibition of AMPK with dorsomorphin. The capacity of cells to accumulate HIF-2α decreased after 24h glucose deprivation. This effect, associated with increased AMPKα phosphorylation, was sensitive to dorsomorphin. In chronically hypoxic cells, glutamine played no major role in HIF-2α accumulation, which became mainly glucose-dependent. Overall, the availability of O2 and metabolic substrates intricately regulates HIF signalling by affecting cell oxygenation, ATP levels and pathways involved in production of HIF-α.
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Affiliation(s)
- Alexander V Zhdanov
- School of Biochemistry and Cell Biology, University College Cork, Cavanagh Pharmacy Building, College Road, Cork, Ireland.
| | - Alicia H C Waters
- School of Biochemistry and Cell Biology, University College Cork, Cavanagh Pharmacy Building, College Road, Cork, Ireland
| | - Anna V Golubeva
- Alimentary Pharmabiotic Centre, University College Cork, Bioscience Institute, Western Road, Cork, Ireland
| | - Dmitri B Papkovsky
- School of Biochemistry and Cell Biology, University College Cork, Cavanagh Pharmacy Building, College Road, Cork, Ireland
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Talaber G, Miklossy G, Oaks Z, Liu Y, Tooze SA, Chudakov DM, Banki K, Perl A. HRES-1/Rab4 promotes the formation of LC3(+) autophagosomes and the accumulation of mitochondria during autophagy. PLoS One 2014; 9:e84392. [PMID: 24404161 PMCID: PMC3880286 DOI: 10.1371/journal.pone.0084392] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2013] [Accepted: 11/22/2013] [Indexed: 02/07/2023] Open
Abstract
HRES-1/Rab4 is a small GTPase that regulates endocytic recycling. It has been colocalized to mitochondria and the mechanistic target of rapamycin (mTOR), a suppressor of autophagy. Since the autophagosomal membrane component microtubule-associated protein light chain 3 (LC3) is derived from mitochondria, we investigated the impact of HRES-1/Rab4 on the formation of LC3(+) autophagosomes, their colocalization with HRES-1/Rab4 and mitochondria, and the retention of mitochondria during autophagy induced by starvation and rapamycin. HRES-1/Rab4 exhibited minimal baseline colocalization with LC3, which was enhanced 22-fold upon starvation or 6-fold upon rapamycin treatment. Colocalization of HRES-1/Rab4 with mitochondria was increased >2-fold by starvation or rapamycin. HRES-1/Rab4 overexpression promoted the colocalization of mitochondria with LC3 upon starvation or rapamycin treatment. A dominant-negative mutant, HRES-1/Rab4(S27N) had reduced colocalization with LC3 and mitochondria upon starvation but not rapamycin treatment. A constitutively active mutant, HRES-1/Rab4(Q72L) showed diminished colocalization with LC3 but promoted the partitioning of mitochondria with LC3 upon starvation or rapamycin treatment. Phosphorylation-resistant mutant HRES-1/Rab4(S204Q) showed diminished colocalization with LC3 but increased partitioning to mitochondria. A newly discovered C-terminally truncated native isoform, HRES-1/Rab4(1-121), showed enhanced localization to LC3 and mitochondria without starvation or rapamycin treatment. HRES-1/Rab4(1-121) increased the formation of LC3(+) autophagosomes in resting cells, while other isoforms promoted autophagosome formation upon starvation. HRES-1/Rab4, HRES-1/Rab4(1-121), HRES-1/Rab4(Q72L) and HRES-1/Rab4(S204Q) promoted the accumulation of mitochondria during starvation. The specificity of HRES-1/Rab4-mediated mitochondrial accumulation is indicated by its abrogation by dominant-negative HRES-1/Rab4(S27N) mutation. The formation of interconnected mitochondrial tubular networks was markedly enhanced by HRES-1/Rab4(Q72L) upon starvation, which may contribute to the retention of mitochondria during autophagy. The present study thus indicates that HRES-1/Rab4 regulates autophagy through promoting the formation of LC3(+) autophagosomes and the preservation of mitochondria.
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Affiliation(s)
- Gergely Talaber
- Departments of Medicine, State University of New York, Upstate Medical University, Syracuse, New York, United States of America
| | - Gabriella Miklossy
- Departments of Medicine, State University of New York, Upstate Medical University, Syracuse, New York, United States of America
| | - Zachary Oaks
- Departments of Medicine, State University of New York, Upstate Medical University, Syracuse, New York, United States of America
- Biochemistry and Molecular Biology, State University of New York, Upstate Medical University, Syracuse, New York, United States of America
| | - Yuxin Liu
- Departments of Medicine, State University of New York, Upstate Medical University, Syracuse, New York, United States of America
| | - Sharon A. Tooze
- Cancer Research UK London Research Institute, London, England, United Kingdom
| | - Dmitriy M. Chudakov
- Shemiakin-Ovchinnikov Institute of Bioorganic Chemistry, RAS, Moscow, Russia
| | - Katalin Banki
- Department of Pathology, State University of New York, Upstate Medical University, Syracuse, New York, United States of America
| | - Andras Perl
- Departments of Medicine, State University of New York, Upstate Medical University, Syracuse, New York, United States of America
- Biochemistry and Molecular Biology, State University of New York, Upstate Medical University, Syracuse, New York, United States of America
- Microbiology and Immunology, State University of New York, Upstate Medical University, Syracuse, New York, United States of America
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Dmitriev RI, Kondrashina AV, Koren K, Klimant I, Zhdanov AV, Pakan JMP, McDermott KW, Papkovsky DB. Small molecule phosphorescent probes for O2imaging in 3D tissue models. Biomater Sci 2014; 2:853-866. [DOI: 10.1039/c3bm60272a] [Citation(s) in RCA: 81] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
PtPFPP-carbohydrate conjugates are promising O2probes for 3D PLIM imaging of live spheroids and brain explants.
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Affiliation(s)
| | | | - Klaus Koren
- Institute of Analytical Chemistry and Food Chemistry
- Graz University of Technology
- 8010 Graz, Austria
| | - Ingo Klimant
- Institute of Analytical Chemistry and Food Chemistry
- Graz University of Technology
- 8010 Graz, Austria
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24
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Zhdanov AV, Dmitriev RI, Hynes J, Papkovsky DB. Kinetic Analysis of Local Oxygenation and Respiratory Responses of Mammalian Cells Using Intracellular Oxygen-Sensitive Probes and Time-Resolved Fluorometry. Methods Enzymol 2014; 542:183-207. [DOI: 10.1016/b978-0-12-416618-9.00010-8] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
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Xu X, Zhang Q, Hu JY, Zhang DX, Jiang XP, Jia JZ, Zhu JC, Huang YS. Phosphorylation of DYNLT1 at serine 82 regulates microtubule stability and mitochondrial permeabilization in hypoxia. Mol Cells 2013; 36:322-32. [PMID: 24170091 PMCID: PMC3887991 DOI: 10.1007/s10059-013-0114-x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2013] [Revised: 07/09/2013] [Accepted: 08/22/2013] [Indexed: 12/19/2022] Open
Abstract
Hypoxia-induced microtubule disruption and mitochondrial permeability transition (mPT) are crucial events leading to fatal cell damage and recent studies showed that microtubules (MTs) are involved in the modulation of mitochondrial function. Dynein light chain Tctex-type 1 (DYNLT1) is thought to be associated with MTs and mitochondria. Previously we demonstrated that DYNLT1 knockdown aggravates hypoxia-induced mitochondrial permeabilization, which indicates a role of DYNLT1 in hypoxic cytoprotection. But the underlying regulatory mechanism of DYNLT1 remains illusive. Here we aimed to investigate the phosphorylation alteration of DYNLT1 at serine 82 (S82) in hypoxia (1% O2). We therefore constructed recombinant adenoviruses to generate S82E and S82A mutants, used to transfect H9c2 and HeLa cell lines. Development of hypoxia-induced mPT (MMP examining, Cyt c release and mPT pore opening assay), hypoxic energy metabolism (cellular viability and ATP quantification), and stability of MTs were examined. Our results showed that phosph-S82 (S82-P) expression was increased in early hypoxia; S82E mutation (phosphomimic) aggravated mitochondrial damage, elevated the free tubulin in cytoplasm and decreased the cellular viability; S82A mutation (dephosphomimic) seemed to diminish the hypoxia-induced injury. These data suggest that DYNLT1 phosphorylation at S82 is involved in MTs and mitochondria regulation, and their interaction and cooperation contribute to the cellular hypoxic tolerance. Thus, we provide new insights into a DYNLT1 mechanism in stabilizing MTs and mitochondria, and propose a potential therapeutic target for hypoxia cytoprotective studies.
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Affiliation(s)
- Xue Xu
- School of Nursing, The Third Military Medical University, Chongqing, China
| | - Qiong Zhang
- Institute of Burn Research, State Key Laboratory of Trauma, Burns and Combined Injury, Southwest Hospital, The Third Military Medical University, Chongqing 400038, China
| | - Jiong-yu Hu
- Institute of Burn Research, State Key Laboratory of Trauma, Burns and Combined Injury, Southwest Hospital, The Third Military Medical University, Chongqing 400038, China
| | - Dong-xia Zhang
- Institute of Burn Research, State Key Laboratory of Trauma, Burns and Combined Injury, Southwest Hospital, The Third Military Medical University, Chongqing 400038, China
| | - Xu-pin Jiang
- Institute of Burn Research, State Key Laboratory of Trauma, Burns and Combined Injury, Southwest Hospital, The Third Military Medical University, Chongqing 400038, China
| | - jie-zhi Jia
- Institute of Burn Research, State Key Laboratory of Trauma, Burns and Combined Injury, Southwest Hospital, The Third Military Medical University, Chongqing 400038, China
| | - Jing-ci Zhu
- School of Nursing, The Third Military Medical University, Chongqing, China
| | - Yue-sheng Huang
- Institute of Burn Research, State Key Laboratory of Trauma, Burns and Combined Injury, Southwest Hospital, The Third Military Medical University, Chongqing 400038, China
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26
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Zhdanov AV, Waters AHC, Golubeva AV, Dmitriev RI, Papkovsky DB. Availability of the key metabolic substrates dictates the respiratory response of cancer cells to the mitochondrial uncoupling. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2013; 1837:51-62. [PMID: 23891695 DOI: 10.1016/j.bbabio.2013.07.008] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/04/2013] [Revised: 07/16/2013] [Accepted: 07/17/2013] [Indexed: 12/12/2022]
Abstract
Active glycolysis and glutaminolysis provide bioenergetic stability of cancer cells in physiological conditions. Under hypoxia, metabolic and mitochondrial disorders, or pharmacological treatment, a deficit of key metabolic substrates may become life-threatening to cancer cells. We analysed the effects of mitochondrial uncoupling by FCCP on the respiration of cells fed by different combinations of Glc, Gal, Gln and Pyr. In cancer PC12 and HCT116 cells, a large increase in O2 consumption rate (OCR) upon uncoupling was only seen when Gln was combined with either Glc or Pyr. Inhibition of glutaminolysis with BPTES abolished this effect. Despite the key role of Gln, addition of FCCP inhibited respiration and induced apoptosis in cells supplied with Gln alone or Gal/Gln. For all substrate combinations, amplitude of respiratory responses to FCCP did not correlate with Akt, Erk and AMPK phosphorylation, cellular ATP, and resting OCR, mitochondrial Ca(2+) or membrane potential. However, we propose that proton motive force could modulate respiratory response to FCCP by regulating mitochondrial transport of Gln and Pyr, which decreases upon mitochondrial depolarisation. As a result, an increase in respiration upon uncoupling is abolished in cells, deprived of Gln or Pyr (Glc). Unlike PC12 or HCT116 cells, mouse embryonic fibroblasts were capable of generating pronounced response to FCCP when deprived of Gln, thus exhibiting lower dependence on glutaminolysis. Overall, the differential regulation of the respiratory response to FCCP by metabolic environment suggests that mitochondrial uncoupling has a potential for substrate-specific inhibition of cell function, and can be explored for selective cancer treatment.
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Affiliation(s)
- Alexander V Zhdanov
- Biochemistry Department, University College Cork, Cavanagh Pharmacy Building, College Road, Cork, Ireland.
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27
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Chronic hypoxia leads to a glycolytic phenotype and suppressed HIF-2 signaling in PC12 cells. Biochim Biophys Acta Gen Subj 2013; 1830:3553-69. [DOI: 10.1016/j.bbagen.2013.02.016] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2012] [Revised: 01/22/2013] [Accepted: 02/15/2013] [Indexed: 12/12/2022]
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Bafilomycin A1 activates HIF-dependent signalling in human colon cancer cells via mitochondrial uncoupling. Biosci Rep 2013; 32:587-95. [PMID: 22943412 PMCID: PMC3497721 DOI: 10.1042/bsr20120085] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Mitochondrial uncoupling is implicated in many patho(physiological) states. Using confocal live cell imaging and an optical O2 sensing technique, we show that moderate uncoupling of the mitochondria with plecomacrolide Baf (bafilomycin A1) causes partial depolarization of the mitochondria and deep sustained deoxygenation of human colon cancer HCT116 cells subjected to 6% atmospheric O2. A decrease in iO2 (intracellular O2) to 0–10 μM, induced by Baf, is sufficient for stabilization of HIFs (hypoxia inducible factors) HIF-1α and HIF-2α, coupled with an increased expression of target genes including GLUT1 (glucose transporter 1), HIF PHD2 (prolyl hydroxylase domain 2) and CAIX (carbonic anhydrase IX). Under the same hypoxic conditions, treatment with Baf causes neither decrease in iO2 nor HIF-α stabilization in the low-respiring HCT116 cells deficient in COX (cytochrome c-oxidase). Both cell types display equal capacities for HIF-α stabilization by hypoxia mimetics DMOG (dimethyloxalylglycine) and CoCl2, thus suggesting that the effect of Baf under hypoxia is driven mainly by mitochondrial respiration. Altogether, by activating HIF signalling under moderate hypoxia, mitochondrial uncoupling can play an important regulatory role in colon cancer metabolism and modulate adaptation of cancer cells to natural hypoxic environments.
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30
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Kondrashina AV, Papkovsky DB, Dmitriev RI. Measurement of cell respiration and oxygenation in standard multichannel biochips using phosphorescent O2-sensitive probes. Analyst 2013; 138:4915-21. [DOI: 10.1039/c3an00658a] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
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31
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Cooper O, Seo H, Andrabi S, Guardia-Laguarta C, Graziotto J, Sundberg M, McLean JR, Carrillo-Reid L, Xie Z, Osborn T, Hargus G, Deleidi M, Lawson T, Bogetofte H, Perez-Torres E, Clark L, Moskowitz C, Mazzulli J, Chen L, Volpicelli-Daley L, Romero N, Jiang H, Uitti RJ, Huang Z, Opala G, Scarffe LA, Dawson VL, Klein C, Feng J, Ross OA, Trojanowski JQ, Lee VMY, Marder K, Surmeier DJ, Wszolek ZK, Przedborski S, Krainc D, Dawson TM, Isacson O. Pharmacological rescue of mitochondrial deficits in iPSC-derived neural cells from patients with familial Parkinson's disease. Sci Transl Med 2012; 4:141ra90. [PMID: 22764206 DOI: 10.1126/scitranslmed.3003985] [Citation(s) in RCA: 387] [Impact Index Per Article: 32.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Parkinson's disease (PD) is a common neurodegenerative disorder caused by genetic and environmental factors that results in degeneration of the nigrostriatal dopaminergic pathway in the brain. We analyzed neural cells generated from induced pluripotent stem cells (iPSCs) derived from PD patients and presymptomatic individuals carrying mutations in the PINK1 (PTEN-induced putative kinase 1) and LRRK2 (leucine-rich repeat kinase 2) genes, and compared them to those of healthy control subjects. We measured several aspects of mitochondrial responses in the iPSC-derived neural cells including production of reactive oxygen species, mitochondrial respiration, proton leakage, and intraneuronal movement of mitochondria. Cellular vulnerability associated with mitochondrial dysfunction in iPSC-derived neural cells from familial PD patients and at-risk individuals could be rescued with coenzyme Q(10), rapamycin, or the LRRK2 kinase inhibitor GW5074. Analysis of mitochondrial responses in iPSC-derived neural cells from PD patients carrying different mutations provides insight into convergence of cellular disease mechanisms between different familial forms of PD and highlights the importance of oxidative stress and mitochondrial dysfunction in this neurodegenerative disease.
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Affiliation(s)
- Oliver Cooper
- Neuroregeneration Institute, McLean Hospital/Harvard Medical School, Belmont, MA 02478, USA
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32
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Papkovskaia TD, Chau KY, Inesta-Vaquera F, Papkovsky DB, Healy DG, Nishio K, Staddon J, Duchen MR, Hardy J, Schapira AHV, Cooper JM. G2019S leucine-rich repeat kinase 2 causes uncoupling protein-mediated mitochondrial depolarization. Hum Mol Genet 2012; 21:4201-13. [PMID: 22736029 PMCID: PMC3441120 DOI: 10.1093/hmg/dds244] [Citation(s) in RCA: 123] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
The G2019S leucine rich repeat kinase 2 (LRRK2) mutation is the most common genetic cause of Parkinson's disease (PD), clinically and pathologically indistinguishable from idiopathic PD. Mitochondrial abnormalities are a common feature in PD pathogenesis and we have investigated the impact of G2019S mutant LRRK2 expression on mitochondrial bioenergetics. LRRK2 protein expression was detected in fibroblasts and lymphoblasts at levels higher than those observed in the mouse brain. The presence of G2019S LRRK2 mutation did not influence LRRK2 expression in fibroblasts. However, the expression of the G2019S LRRK2 mutation in both fibroblast and neuroblastoma cells was associated with mitochondrial uncoupling. This was characterized by decreased mitochondrial membrane potential and increased oxygen utilization under basal and oligomycin-inhibited conditions. This resulted in a decrease in cellular ATP levels consistent with compromised cellular function. This uncoupling of mitochondrial oxidative phosphorylation was associated with a cell-specific increase in uncoupling protein (UCP) 2 and 4 expression. Restoration of mitochondrial membrane potential by the UCP inhibitor genipin confirmed the role of UCPs in this mechanism. The G2019S LRRK2-induced mitochondrial uncoupling and UCP4 mRNA up-regulation were LRRK2 kinase-dependent, whereas endogenous LRRK2 levels were required for constitutive UCP expression. We propose that normal mitochondrial function was deregulated by the expression of G2019S LRRK2 in a kinase-dependent mechanism that is a modification of the normal LRRK2 function, and this leads to the vulnerability of selected neuronal populations in PD.
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Affiliation(s)
- Tatiana D Papkovskaia
- Department of Clinical Neurosciences, Institute of Neurology, University College London, London NW3 2PF, UK
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33
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Dmitriev RI, Zhdanov AV, Jasionek G, Papkovsky DB. Assessment of Cellular Oxygen Gradients with a Panel of Phosphorescent Oxygen-Sensitive Probes. Anal Chem 2012; 84:2930-8. [DOI: 10.1021/ac3000144] [Citation(s) in RCA: 69] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
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34
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Optical probes and techniques for O2 measurement in live cells and tissue. Cell Mol Life Sci 2012; 69:2025-39. [PMID: 22249195 PMCID: PMC3371327 DOI: 10.1007/s00018-011-0914-0] [Citation(s) in RCA: 138] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2011] [Revised: 12/19/2011] [Accepted: 12/29/2011] [Indexed: 01/03/2023]
Abstract
In recent years, significant progress has been achieved in the sensing and imaging of molecular oxygen (O2) in biological samples containing live cells and tissue. We review recent developments in the measurement of O2 in such samples by optical means, particularly using the phosphorescence quenching technique. The main types of soluble O2 sensors are assessed, including small molecule, supramolecular and particle-based structures used as extracellular or intracellular probes in conjunction with different detection modalities and measurement formats. For the different O2 sensing systems, particular attention is paid to their merits and limitations, analytical performance, general convenience and applicability in specific biological applications. The latter include measurement of O2 consumption rate, sample oxygenation, sensing of intracellular O2, metabolic assessment of cells, and O2 imaging of tissue, vasculature and individual cells. Altogether, this gives the potential user a comprehensive guide for the proper selection of the appropriate optical probe(s) and detection platform to suit their particular biological applications and measurement requirements.
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Fercher A, Zhdanov AV, Papkovsky DB. O2 Imaging in Biological Specimens. PHOSPHORESCENT OXYGEN-SENSITIVE PROBES 2012. [DOI: 10.1007/978-3-0348-0525-4_3] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
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36
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Fang YD, Xu X, Dang YM, Zhang YM, Zhang JP, Hu JY, Zhang Q, Dai X, Teng M, Zhang DX, Huang YS. MAP4 mechanism that stabilizes mitochondrial permeability transition in hypoxia: microtubule enhancement and DYNLT1 interaction with VDAC1. PLoS One 2011; 6:e28052. [PMID: 22164227 PMCID: PMC3229508 DOI: 10.1371/journal.pone.0028052] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2011] [Accepted: 10/31/2011] [Indexed: 01/22/2023] Open
Abstract
Mitochondrial membrane permeability has received considerable attention recently because of its key role in apoptosis and necrosis induced by physiological events such as hypoxia. The manner in which mitochondria interact with other molecules to regulate mitochondrial permeability and cell destiny remains elusive. Previously we verified that hypoxia-induced phosphorylation of microtubule-associated protein 4 (MAP4) could lead to microtubules (MTs) disruption. In this study, we established the hypoxic (1% O2) cell models of rat cardiomyocytes, H9c2 and HeLa cells to further test MAP4 function. We demonstrated that increase in the pool of MAP4 could promote the stabilization of MT networks by increasing the synthesis and polymerization of tubulin in hypoxia. Results showed MAP4 overexpression could enhance cell viability and ATP content under hypoxic conditions. Subsequently we employed a yeast two-hybrid system to tag a protein interacting with mitochondria, dynein light chain Tctex-type 1 (DYNLT1), by hVDAC1 bait. We confirmed that DYNLT1 had protein-protein interactions with voltage-dependent anion channel 1 (VDAC1) using co-immunoprecipitation; and immunofluorescence technique showed that DYNLT1 was closely associated with MTs and VDAC1. Furthermore, DYNLT1 interactions with MAP4 were explored using a knockdown technique. We thus propose two possible mechanisms triggered by MAP4: (1) stabilization of MT networks, (2) DYNLT1 modulation, which is connected with VDAC1, and inhibition of hypoxia-induced mitochondrial permeabilization.
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Affiliation(s)
- Ya-dong Fang
- State Key Laboratory for Trauma, Burn and Combined Injury, Institute of Burn Research, Southwest Hospital, Third Military Medical University, Chongqing, China
| | - Xue Xu
- The No. 324 Hospital of PLA, Chongqing, China
| | - Yong-ming Dang
- State Key Laboratory for Trauma, Burn and Combined Injury, Institute of Burn Research, Southwest Hospital, Third Military Medical University, Chongqing, China
| | - Yi-ming Zhang
- Department of Plastic and Cosmetic Surgery, Xinqiao Hospital, Third Military Medical University, Chongqing, China
| | - Jia-ping Zhang
- State Key Laboratory for Trauma, Burn and Combined Injury, Institute of Burn Research, Southwest Hospital, Third Military Medical University, Chongqing, China
| | - Jiong-yu Hu
- State Key Laboratory for Trauma, Burn and Combined Injury, Institute of Burn Research, Southwest Hospital, Third Military Medical University, Chongqing, China
| | - Qiong Zhang
- State Key Laboratory for Trauma, Burn and Combined Injury, Institute of Burn Research, Southwest Hospital, Third Military Medical University, Chongqing, China
| | - Xia Dai
- Department of Plastic and Cosmetic Surgery, Southwest Hospital, Third Military Medical University, Chongqing, China
| | - Miao Teng
- State Key Laboratory for Trauma, Burn and Combined Injury, Institute of Burn Research, Southwest Hospital, Third Military Medical University, Chongqing, China
| | - Dong-xia Zhang
- State Key Laboratory for Trauma, Burn and Combined Injury, Institute of Burn Research, Southwest Hospital, Third Military Medical University, Chongqing, China
| | - Yue-sheng Huang
- State Key Laboratory for Trauma, Burn and Combined Injury, Institute of Burn Research, Southwest Hospital, Third Military Medical University, Chongqing, China
- * E-mail:
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Jacoby J, Kreitzer MA, Alford S, Qian H, Tchernookova BK, Naylor ER, Malchow RP. Extracellular pH dynamics of retinal horizontal cells examined using electrochemical and fluorometric methods. J Neurophysiol 2011; 107:868-79. [PMID: 22090459 DOI: 10.1152/jn.00878.2011] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Extracellular H(+) has been hypothesized to mediate feedback inhibition from horizontal cells onto vertebrate photoreceptors. According to this hypothesis, depolarization of horizontal cells should induce extracellular acidification adjacent to the cell membrane. Experiments testing this hypothesis have produced conflicting results. Studies examining carp and goldfish horizontal cells loaded with the pH-sensitive dye 5-hexadecanoylaminofluorescein (HAF) reported an extracellular acidification on depolarization by glutamate or potassium. However, investigations using H(+)-selective microelectrodes report an extracellular alkalinization on depolarization of skate and catfish horizontal cells. These studies differed in the species and extracellular pH buffer used and the presence or absence of cobalt. We used both techniques to examine H(+) changes from isolated catfish horizontal cells under identical experimental conditions (1 mM HEPES, no cobalt). HAF fluorescence indicated an acidification response to high extracellular potassium or glutamate. However, a clear extracellular alkalinization was found using H(+)-selective microelectrodes under the same conditions. Confocal microscopy revealed that HAF was not localized exclusively to the extracellular surface, but rather was detected throughout the intracellular compartment. A high degree of colocalization between HAF and the mitochondrion-specific dye MitoTracker was observed. When HAF fluorescence was monitored from optical sections from the center of a cell, glutamate produced an intracellular acidification. These results are consistent with a model in which depolarization allows calcium influx, followed by activation of a Ca(2+)/H(+) plasma membrane ATPase. Our results suggest that HAF is reporting intracellular pH changes and that depolarization of horizontal cells induces an extracellular alkalinization, which may relieve H(+)-mediated inhibition of photoreceptor synaptic transmission.
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Affiliation(s)
- Jason Jacoby
- Department of Biological Sciences, University of Illinois at Chicago, Chicago, Illinois, USA
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38
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Dmitriev RI, Ropiak HM, Ponomarev GV, Yashunsky DV, Papkovsky DB. Cell-Penetrating Conjugates of Coproporphyrins with Oligoarginine Peptides: Rational Design and Application for Sensing Intracellular O2. Bioconjug Chem 2011; 22:2507-18. [DOI: 10.1021/bc200324q] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Affiliation(s)
- Ruslan I. Dmitriev
- Biochemistry Department, University College Cork, Cavanagh Pharmacy Building,
Cork, Ireland
| | - Honorata M. Ropiak
- Biochemistry Department, University College Cork, Cavanagh Pharmacy Building,
Cork, Ireland
| | - Gelii V. Ponomarev
- Institute
of Biomedical Chemistry, Russian Academy of Medical Sciences, Pogodinskaia Ul.
10/2, 119992 Moscow, Russia
| | - Dmitri V. Yashunsky
- Institute
of Biomedical Chemistry, Russian Academy of Medical Sciences, Pogodinskaia Ul.
10/2, 119992 Moscow, Russia
| | - Dmitri B. Papkovsky
- Biochemistry Department, University College Cork, Cavanagh Pharmacy Building,
Cork, Ireland
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39
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Zhdanov AV, Favre C, O'Flaherty L, Adam J, O'Connor R, Pollard PJ, Papkovsky DB. Comparative bioenergetic assessment of transformed cells using a cell energy budget platform. Integr Biol (Camb) 2011; 3:1135-42. [PMID: 22005712 DOI: 10.1039/c1ib00050k] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
The aberrant expression and functional activity of proteins involved in ATP production pathways may cause a crisis in energy generation for cells and compromise their survival under stressful conditions such as excitation, starvation, pharmacological treatment or disease states. Under resting conditions such defects are often compensated for, and therefore masked by, alternative pathways which have significant spare capacity. Here we present a multiplexed 'cell energy budget' platform which facilitates metabolic assessment and cross-comparison of different cells and the identification of genes directly or indirectly involved in ATP production. Long-decay emitting O(2) and pH sensitive probes and time-resolved fluorometry are used to measure changes in cellular O(2) consumption, glycolytic and total extracellular acidification (ECA), along with the measurement of total ATP and protein content in multiple samples. To assess the extent of spare capacity in the main energy pathways, the cells are also analysed following double-treatment with carbonyl cyanide p-(trifluoromethoxy)phenylhydrazone and oligomycin. The four-parametric platform operating in a high throughput format has been validated with two panels of transformed cells: mouse embryonic fibroblasts (MEFs) lacking the Krebs cycle enzyme fumarate hydratase (Fh1) and HeLa cells with reduced expression of pyrimidine nucleotide carrier 1. In both cases, a marked reduction in both respiration and spare respiratory capacity was observed, accompanied by a compensatory activation of glycolysis and consequent maintenance of total ATP levels. At the same time, in Fh1-deficient MEFs the contribution of non-glycolytic pathways to the ECA did not change.
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Affiliation(s)
- A V Zhdanov
- Biochemistry Department, University College Cork, Cavanagh Pharmacy Building, College Road, Cork, Ireland
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Fercher A, Borisov SM, Zhdanov AV, Klimant I, Papkovsky DB. Intracellular O2 sensing probe based on cell-penetrating phosphorescent nanoparticles. ACS NANO 2011; 5:5499-5508. [PMID: 21671589 DOI: 10.1021/nn200807g] [Citation(s) in RCA: 134] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
A new intracellular O(2) (icO(2)) sensing probe is presented, which comprises a nanoparticle (NP) formulation of a cationic polymer Eudragit RL-100 and a hydrophobic phosphorescent dye Pt(II)-tetrakis(pentafluorophenyl)porphyrin (PtPFPP). Using the time-resolved fluorescence (TR-F) plate reader set-up, cell loading was investigated in detail, particularly the effects of probe concentration, loading time, serum content in the medium, cell type, density, etc. The use of a fluorescent analogue of the probe in conjunction with confocal microscopy and flow cytometry analysis, revealed that cellular uptake of the NPs is driven by nonspecific energy-dependent endocytosis and that the probe localizes inside the cell close to the nucleus. Probe calibration in biological environment was performed, which allowed conversion of measured phosphorescence lifetime signals into icO(2) concentration (μM). Its analytical performance in icO(2) sensing experiments was demonstrated by monitoring metabolic responses of mouse embryonic fibroblast cells under ambient and hypoxic macroenvironment. The NP probe was seen to generate stable and reproducible signals in different types of mammalian cells and robust responses to their metabolic stimulation, thus allowing accurate quantitative analysis. High brightness and photostability allow its use in screening experiments with cell populations on a commercial TR-F reader, and for single cell analysis on a fluorescent microscope.
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Affiliation(s)
- Andreas Fercher
- Biochemistry Department, University College Cork, Cavanagh Building, College Road, Cork, Ireland
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